Here are my tricks to cleaning the throttle body:
-get a throttle body cleaner that can spray upside-down. This is very important for most sprays cannot do that.
-get a cleaner that is made specifically for cleaning throttle body only, and specifies that it will not dissolve/damage/corrode the coating on the throttle body(venturi section). There are some kind of PTFE or similar coating inside that is unique to most EFI cars and not in older carburettor car systems. Make absolutely sure that you get a cleaner that is sensor-safe(O2 sensor, throttle body coating, etc.)
-While I like Stooge's idea of using some old cotton sock (make sure it doesn't shed lint and it's of pure cotton variety) and an old toothbrush, I personally use heavy duty shop paper towel that doesn't shed lint.
After you have warmed up your engine, carefully undo the air duct clamp and twist it out.
Next, with a flashlight or similar light source on one hand, you twist the throttle valve using the other hand and inspect the throttle condition. Carbon buildup usually appears on the lip side of the throttle plate.
Next, you'll have to determine if there exists a big hole inside the throttle body, with your throttle plate closed. This shall, under normal circumstance, your IAC inlet portion.
Now, with the throttle plate cracked open, you lightly wet down the lip portion with cleaner and depending on the buildup, you may either wipe it down with old cotton sock or scrub it lightly with toothbrush. Make absolutely sure you do not get any lint or nylon bristles into the throttle body bore.
*note: you may have to poke your finger deep into the throttle body in order to wipe down the other inner-bottom side of the throttle plate. Make sure you do that to the best of your ability.
Make sure you wipe dry your throttle body as quickly as possible.
now, with throttle plate closed, carefully spray some cleaner into the big hole outside of the throttle plate. Usually 1 or 2 short burst should be fine. Let sit for about 20 secs before you re-assemble everything and start your engine again. Let it idle for 5 mins to clear all the cleaners before you repeat this process (of cleaning the IAC orifice/mechanism) until you are satisfied (usually, a regularly maintained throttle body, the IAC valve only needs 1 rounds of 2 short bursts and then that's it. Dirty ones or one that hasn't been serviced since day-1 may require 2~3 rounds of squirts, re-assemble-->run-->disassemble and then spray again).
Caution: Use throttle body cleaner sparingly. Do not intentionally "Wet" the entire throttle body with cleaner (as opposed to many believer's practice). Just spray enough cleaner to wet the dirty portion and then wipe it down. Better yet: try wetting the sock or towel portion and then wipe the throttle plate down if possible. This is to minimise/eliminate the possibility of solvent attacks to some rubber o-rings/seals and elastomeric materials inside many throttle body assemblies and further emission control attachments (sensors).
try to identify the big IAC hole to the best of your abilities and DO NOT, I repeat, DO NOT spray or get cleaner into any other smaller holes on the throttle body, behind the throttle plate. These are mostly vacuum related devices and are driven by rubber vacuum hoses and rubber membrane and will develop holes/deterioriate if you get solvent cleaner in them.
*whew*
Q.
(that should help you save $150)
